4-9 圆形边框

来源：4-10 编程练习

BruinK

2018-06-19 10:56:43

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>案例</title>
    <style>
        canvas{background-color:lightblue;}
    </style>
</head>
<body>
    <canvas id="canvas" width="600px" height="600px">您的浏览器不支持</canvas>
    <script>
        var canvas=document.getElementById("canvas");
        var ctx=canvas.getContext("2d");
        ctx.translate(300,300);
          ctx.fillStyle="#ffb6c1";
          ctx.arc(0,0,100,0,2*Math.PI,true);
          ctx.fill();
          for(var i=0;i<4;i++){
              ctx.rotate(Math.PI/2);
               ctx.moveTo(90,0);
              ctx.lineTo(100,0);
          }
          ctx.moveTo(0,0);
          ctx.lineTo(80,0);
          ctx.moveTo(0,0);
          ctx.lineTo(0,-70);
          ctx.stroke();
         
    </script>
</body>
</html>

这个圆形的外边框怎么去掉？